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Charles T. Kowal (1940–2011)

Kowal was widely known for his discoveries and observations of small solar system bodies — especially for the 1977 discovery of 2060 Chiron, the first of the Centaur-class of asteroids.

Published onOct 18, 2022
Charles T. Kowal (1940–2011)

Kowal circa 1990. Photo credit: Albert V. Holm.

Charles Thomas Kowal (Charlie) passed away on Monday November 28, 2011 in Cinebar, Washington. He was 71.

Kowal was widely known for his discoveries and observations of small solar system bodies and especially for the 1977 discovery of 2060 Chiron, the first and among the largest of the Centaur-class of asteroids which have unstable orbits lying between Jupiter and Neptune. It was subsequently found to have a comet-like coma. He is also credited with the discovery of two satellites of Jupiter, Leda and Themisto, and the discovery or co-discovery of several asteroids, comets, and supernovae. In 1979 he was awarded the James Craig Watson Medal of the U. S. National Academy of Sciences for his contributions. A crater on Pluto is named in his honor.

Charlie was born in Buffalo, New York on November 8, 1940 to Charles Joseph and Rose (Myszkowiak) Kowal. The 1950 census shows him as a 9-year-old living with his parents with no siblings; Grandma Kowal lived next door. His father was a hammerman at a local forge, and his mother was a baker. Although within the city limits of Buffalo, the house was surrounded by open fields where the budding astronomer could set up his home-made telescope. He graduated from Buffalo’s East High School in 1957, and the yearbook shows that he was active in the Chess and International Clubs, was on the Honor Roll, and that his ambition was to be an astronomer.

Despite being a long way from home, he applied and was accepted to the University of Southern California in Los Angeles. He knew that the clearest skies and biggest telescopes were in the Southwest, so that was his destination. He worked part-time as a night assistant at the Mt. Wilson and Palomar Observatories, graduating with a B.A. in Astronomy in 1963. From 1960 until his graduation, he worked on Allan Sandage’s project to obtain UBV photometry of 1690 high-proper-motion stars with the aim of studying the relation between kinematics and metal abundance [1].

As Kowal stated in an interview with Time magazine years later (Oct. 27, 1975), he had no interest in graduate school but just wanted to observe on anybody’s program that would support him. “I know nothing about astrophysics or electrodynamics. All I’m good at is using a telescope."

This indeed was good enough for Fritz Zwicky to hire him as an observer on the Oschin 1.22-m Schmidt camera on Mt. Palomar to provide observations for his six-volume Catalogue of Galaxies and of Clusters of Galaxies; Kowal was a co-author on Vols. 1, 5 and 6. Charlie worked on all the telescopes at both sites, but the large Schmidt was his favorite. Being a Schmidt, it was an entirely photographic operation employing glass plates 35.6 cm on a side covering 6.6 degrees (area of 43.6 square degrees). Loading, exposing, and developing such large plates without breakage required care and skill, and Kowal was a master at it. Later, pre-exposure hypersensitizing processes were introduced that required even more handling.

Zwicky was an early proponent of using Type Ia supernovae as distance indicators to faint galaxies since they had similar intrinsic properties, and in 1959 he started a systematic search for them on Oschin Schmidt plates (the Palomar Supernova Search). Kowal was one of several observers on the program and was active in the scrutiny of the plates. Each discovery required at least two plates which were examined in a blink comparator. By the time the Zwicky SN search on the Oschin Schmidt was terminated in Dec. 1975, 178 had been found, 81 by Kowal. Countless other variable stars of interest were also noted and published.

Occasional short streaks on long-exposure plates taken near the ecliptic caught his attention and became the focus of his work from about 1970 to his retirement some 35 years later, pivoting from searches for SNe in distant galaxies to surveying for asteroids and comets in the nearby Solar System. Due to its wide field and superb images, the big Schmidt was ideal for this work, and Kowal pushed the approach to its limits. The method was to take two identical plates on the same center a few hours apart and at about the same zenith distance to minimize differential refraction and search for anything that moved. Thus, it might be said that he spent more time at the eyepiece of the blink machine than he did at the eyepiece of the guide scope on the Schmidt. This effort led to his discovery or co-discovery of several notable asteroids in the Main Belt, recovery of some ‘lost’ asteroids, a few Trojan asteroids, and several periodic comets. Most of these discoveries were published in the Circulars of the IAU Central Bureau for Astronomical Telegrams; his frequent collaborators were Richard McCrosky, Elizabeth Roemer, and Brian Marsden.

As stated above, in the mid-1970’s Kowal found two new satellites of Jupiter, J XIII (Leda) and J XVIII (Themisto), the latter jointly with E. Roemer. In 1977 he initiated a survey of 6400 square degrees along the ecliptic searching for slow-moving objects beyond the Main Belt resulting in the discovery of the important body 1977 UB = 2060 Chiron, unique at that time. Since it was found early in this survey, he strove to find others but was not successful; the next Centaur was not found until 15 years later by David Rabinowitz in the Spacewatch Program at the University of Arizona.

Charlie also made a startling non-telescopic discovery through close attention to the literature. The March 1979 issue of Sky and Telescope magazine had an article by Steven Albers listing mutual occultations of planets from 1557 to 2230, and among these was an occultation of Neptune by Jupiter in January 1613. Kowal quickly realized that Galileo was observing Jupiter at this time and might have seen Neptune. With help from the Hale Observatories librarians, he found reproductions of Galileo’s notebooks with drawings of Jupiter and its satellites for December 28, 1612 and a ‘star’ which was not in the Smithsonian Astrophysical Observatory Catalog. Furthermore, Galileo noted that this ‘star’ moved slightly with respect to a true SAO star over several nights. So, Galileo had seen Neptune over 200 years before its accepted discovery in 1846. Kowal gives the details of his detective work in DIO The International Journal of Scientific History [2].

In 1985 Kowal came back East to Baltimore to accept an operations astronomer job with Computer Sciences Corp., a sub-contractor to AURA which was charged with operating the Hubble Space Telescope at the Space Telescope Science Institute (STScI). He worked in the Observation Support System (OSS) division developing and testing software to observe Solar System objects — ‘moving targets’ in the lingo. This was several years before the 1990 launch, and the time was well spent in developing a robust system. Other moving-target astronomers in the group were Eddie Wells and Ben Zellner. Once launched, they and others in OSS monitored the instruments and data stream in real time. In his spare time, he published the book Asteroids: Their Nature and Utilization in 1988 with a second edition in 1996.

That same year he left STScI and joined the team operating the Near-Earth Asteroid Rendezvous (NEAR) Shoemaker robotic spacecraft which orbited and landed on asteroid 433 Eros. This mission was developed and run from Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland. Kowal also developed the command sequence for the flyby of 243 Mathilde and later worked on attitude control of the Earth orbiter Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) mission. He retired from APL in June 2006 and moved back West to tiny Cinebar, Washington. He loved the outdoors and wanted to be surrounded by nature.

Personal note: This author had the pleasure of sharing an office with Kowal at STScI for a few years and enjoyed his good spirits and unflappable nature. Notwithstanding his considerable achievements, he was quiet and self-effacing and enjoyed a good laugh on himself. He was an inspiration to amateur astronomers who saw that significant contributions were possible without an advanced degree.

He met his wife, Maria Antonietta Ruffino, in Italy and they were married there in October 1968; their daughter was born in Los Angeles a year later.

He is survived by his widow, daughter Loretta (Lory) Kowal Marciniak, and grandsons Cameron Gregory and Brandon Charles Marciniak.

It is a pleasure to acknowledge information provided by Helen Hart, Albert V. Holm, and Lory Marciniak.

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